S. GAIT

tendinosus, semi-membranosus, gracilis, and sartorius, forming the Inner
Hamstring. Action, to flex the leg and rotate it outwards. Nerve, great
sciatic.
r son lo

Semi-tendinosus, from the tuberosity of the ischium by a tendon1 common
to it and the long head of the biceps, and from the adjacent aponeurosis,—
into the shaft of the tibia at its upper and inner surface, its tendon curving
around the inner tuberosity. Action, to flex the leg upon the thigh. Nerve,
great sciatic
callc

Semi-membranosus,g from the tuberosity of the ischium above the origin of the above-named muscles,-into the inner tuberosity of the tibia; its tendon dividing into 3 parts, one over the popliteus muscle, and another forming the posterior ligament of the knee-joint. Action, to flex the leg, and rotate it inwards. Nerve, great sciatic.

External Rotators of the Hip-joint are 122,-the 3 adductors, pyriformis, 2 obturators, 2 gemelli, pectineus, psoas magnus, iliacus, sartorius, and posterior half of the gluteus medius.

Internal Rotators of the Hip-joint are 21⁄2,—the tensor vaginæ femoris, gluteus minimus, and the anterior half of the gluteus medius.

MUSCLES OF THE LEG.

Muscles of the leg arranged in groups of threes. (Pancoast.)

Flexor Longus Pollicis.
Flexor Longus Digitorum.
Peroneus Longus.

Peroneus Brevis.

ha Peroneus Tertius

Tibialis Anti'cus3 (Flexor Tarsi Tibialis), from the outer tuberosity and upper two-thirds of the shaft of the tibia externally, the interosseous membrane, deep fascia, and intermuscular septum,-through the inner canal in the anterior annular ligament into the inner and plantar surface of the internal cuneiform bone, and the base of the 1st metatarsal. Action, to flex the tarsus on the leg, and elevate the inner border of the foot. Nerve, anterior tibial. Extensor Proprius Pollicis,5 from the middle two-fourths of the fibula anteriorly and the interosseous membrane,—through the 2d canal in the anterior annular ligament,—into the base of the last phalanx of the great toe. Action, to extend that toe. Nerve, anterior tibia!.

Extensor Longus Digitorum, from the outer tuberosity of the tibia, the upper three-fourths of the shaft of the fibula anteriorly, interosseous membrane, deep fascia, and intermuscular septa,-into the 2d and 3d phalanges of the

4 lesser toes, by 4 tendons which pass over the dorsum of the foot, from the outer canal in the anterior annular ligament.

FIG. 50.

Action, to extend the lesser toes, Nerve, anterior tibial. Lenton of But. cony. Dig. Peroneus Tertius6 (Flexor Tarsi Fibularis), from the outer lower one-fourth of the fibula, interosseous membrane, and intermuscular septum,- into the base of the 5th metatarsal bone. This muscle is a part of the last named, and passes through the same canal in the annular ligament. Action, to flex the tarsus. Nerve, anterior tibial. Gastrocnemius, by 2 heads from the condyles of the femur, and the supra-condyloid ridges,-unites with the tendon of the soleus to form the tendo Achillis, into the posterior tuberosity of the os calcis. Action, to extend the foot. Nerve, internal popliteal. Br Soleus, from the head and upper one-half of the shaft of the fibula posteriorly, the oblique line of the tibia, and the tendinous arch,-unites with the tendon of the gastrocnemius as the tendo Achillis (see above). Action, to extend the foot. Nerve, internal popliteal.

Plantaris, from the outer bifurcation of the linea aspera, and posterior ligament of the knee-joint, by a very long, delicate tendon,-into the posterior surface of the os calcis. Action, to extend the foot. Nerve, internal popliteal.

Popliteus, from a depression on the external condyle of the femur, and the posterior ligament of the knee. joint,-into the inner two-thirds of the triangular surface on the shaft of the tibia posteriorly and above the oblique line. Action, to flex the leg. Nerve, internal popliteal.

Flexor Longus Pollicis, from the lower two-thirds of the shaft of the fibula internally, the interosseous membrane, fascia, and intermuscular septum,-through grooves in the tibia, astragalus, and os calcis,-into the base of the last phalanx of the great toe. Action, to flex the great toe. Nerve, posterior tibial.

Flexor Longus Digitorum, from the shaft of the tibia posteriorly and below the oblique line, and the intermuscular septum,-passes behind the inner malleolus in a groove13 with the tibialis posticus,-into the bases of

the last phalanges of the lesser toes by 4 tendons which perforate the tendons of the flexor brevis digitorum. Action, to flex the phalanges and extend the foot. Nerve, posterior tibial. Boiled. Tibialis Posti'cus, by two processes between which pass the anterior tibial vessels, from the upper one-half of shaft of the tibia posteriorly, the upper two-thirds of the shaft of the fibula internally, the interosseous membrane, deep fascia, and intermuscular septa,-passes behind the inner malleolus in a groove 13 with the long flexor, into the tuberosity of the scaphoid and internal cuneiform bones. Action, to extend the tarsus, and invert the foot. Nerve, posterior tibial. Peroneus Longus,10 from the head of the fibula and the upper two-thirds of its shaft externally, the deep fascia, and intermuscular septa,-passes behind the outer malleolus in a groove with the peroneus brevis, through a groove in the cuboid bone, to the outer side of the base of the Ist metatarsal bone. Action, to extend and evert the foot. Nerve, musculo-cutaneous. Peroneus Brevis,11 from the middle one-third of the shaft of the fibula externally, and the intermuscular septa,passes behind the external malleolus in a groove with the long peroneal, into the dorsum of the base of the 5th metatarsal bone. Action, to extend the foot. Nerve, musculo-cutaneous branch of external popliteal.

FASCIE OF THE FOOT.

ANTERIOR ANNULAR LIGAMENT, consists of vertical and horizontal portions, is attached to the lower ends of the fibula and tibia, the os calcis and the plantar fascia. It contains 5 sheaths lined by synovial membranes for the tendons of the extensor muscles, that of the extensor proprius pollicis passing beneath it, as also the anterior tibial vessels and nerve.

INTERNAL ANNULAR LIGAMENT, from the inner malleolus to the os calcis, converting 3 bony grooves into canals lined by synovial membranes for the flexor tendons and the posterior tibial vessels and nerve.

EXTERNAL ANNULAR LIGAMENT, from the outer malleolus to the os calcis, binding down the peronei tendons in one synovial sac.

PLANTAR FASCIA, the densest in the body, divided into a central and two lateral portions, and attached to the inner tuberosity of the os calcis, divides into 5 processes, I for each toe, and several intermuscular septa.

MUSCLES OF THE FOOT.

Extensor Brevis Digitorum, the only muscle on the dorsum of the foot, arises from the os calcis externally, the astragalo-calcanean and the anterior annular ligaments,-by 4 tendons, I into the 1st phalanx of the great toe, and the others into the outer sides of the long extensor tendons of the 2d, 3d, and 4th toes. Action, to extend the toes. Nerve, anterior tibial. Muscles on the sole of the foot (19), by layers :

Abductor Pollicis,a from the inner tuberosity of the os calcis, the internal annular ligament, plantar fascia, and intermuscular septum,-into the inner side of the base of the 1st phalanx of the great toe. Action, to abduct the great toe. Nerve, internal plantar.

Flexor Brevis Digitorum, from the inner tuberosity of the os calcis, the plantar fascia and intermuscular septa,-into the sides of the 2d pha

langes of the lesser toes by 4 tendons which are perforated for the long flexor tendons. Action, to flex the lesser toes. Nerve, internal plantar.

Abductor Minimi Digiti,h from the outer tuberosity and under surface of the os calcis, the plantar fascia and the intermuscular septum,into the base of the 1st phalanx of the little toe with the tendon of its short flexor. Action, to abduct the little toe. Nerve, external plantar. Flexor Accessorius, by 2 heads, from the os calcis and the calcaneo-scaphoid and long plantar ligaments,-into the tendon of the flexor longus digitorum. Action, accessory flexor of the toes. Nerve, external plantar.

Lumbricales (4), from the long flexor tendons -into the inner side of the second phalanges of the lesser toes. Action, accessory flexors. Nerves, internal plantar to the two internal, external plantar to the others.

Flexor Brevis Pollicis, from the cuboid and external cuneiform bones, and the prolonged tendon of the tibialis posticus,-into both sides of the base of the Ist phalanx of the great toe, by 2 portions, of which one blends with the abductor pollicis, the other with the adductor pollicis. Action, to flex the great toe. Nerve, internal plantar. Adductor Pollicis, from the tarsal ends of the three middle metatarsal bones, and the sheath of the tendon of the peroneus longus,—into the base of the Ist phalanx of the great toe, externally. Action, to adduct the great toe. Nerve, external plantar.

Flexor Brevis Minimi Digiti,¿ from the base of the 5th metatarsal bone and the sheath of the tendon of the peroneus longus,-into the base of the Ist phalanx of the little toe externally. Action, to flex the little toe. Nerve, external plantar.

Transversus Pedis, from the under surface of the head of the 5th metatarsal bone, and the transverse ligament of the metatarsus,-into the outer side of the Ist phalanx of the great toe, blending with the tendon of the adductor pollicis. Action, to adduct the great toe. Nerve, external plantar. Dorsal Interossei (4), each by two heads from the adjacent sides of two metatarsal bones,—into the base of the 1st phalanx of the corresponding toe. Action, to abduct the toes. Nerve, external plantar.

Plantar Interosseij (3), from the shafts of the 3d, 4th, and 5th metatarsal bones,-into the bases of the 1st phalanges of the same toes. Action, to adduct the toes towards the median line. Nerve, external plantar.

THE HEART.

What is the Pericardium ? It is a conical membranous closed sac, containing the heart and the roots of the great vessels. It lies behind the sternum and between the pleuræ, its apex upwards, its base below and attached to the central tendon of the diaphragm. It is composed of an outer fibrous coat, and an inner serous one; the latter consisting of two portions, a parietal layer, lining the inner surface of the fibrous coat, and a visceral layer, which is reflected over the heart and vessels. The serous portion secretes a thin fluid, about I drachm in quantity normally, for the lubrication of its surfaces. The fibrous coat is prolonged on the outer surfaces of the great vessels, except the inferior vena cava, and becomes continuous with the deep layer of the cervical fascia.

Describe the Endocardium. It is a serous membrane which lines the inner surface of the heart, forming by its reduplications the cardiac, aortic, and pulmonary valves, and continuous with the lining membrane of the great ssels.